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While consuming a low dose of pathogenic bacterium is associated with a low probability of disease, infection is still possible. This contributes to sporadic cases of food-borne illness in the population. There is no bacterial concentration in food below which a lack of epidemic is guaranteed.
The minimum bactericidal concentration (MBC) is the lowest concentration of an antibacterial agent required to kill a particular bacterium. [1] It can be determined from broth dilution minimum inhibitory concentration (MIC) tests by subculturing to agar plates that do not contain the test agent.
Human infectious diseases may be characterized by their case fatality rate (CFR), the proportion of people diagnosed with a disease who die from it (cf. mortality rate).It should not be confused with the infection fatality rate (IFR), the estimated proportion of people infected by a disease-causing agent, including asymptomatic and undiagnosed infections, who die from the disease.
Bacteria are marked as sensitive, resistant, or having intermediate resistance to an antibiotic based on the minimum inhibitory concentration (MIC), which is the lowest concentration of the antibiotic that stops the growth of bacteria. The MIC is compared to standard threshold values (called "breakpoints") for a given bacterium and antibiotic. [28]
While the MIC is the lowest concentration of an antibacterial or antifungal agent necessary to inhibit visible growth, the minimum bactericidal concentration (MBC) is the minimum concentration of an antibacterial agent that results in bacterial death. It is defined by the inability to re-culture bacteria, and the closer the MIC is to the MBC ...
In the case of mesophilic bacteria, the response time range from 2 – 3 hours for highly contaminated samples (10 5 - 10 6 cfu/ml) to over 10 hours for samples with very low bacterial concentration (less than 10 cfu/ml). As a comparison, for the same bacterial strains the Plate Count technique is characterized by response times from 48 to 72 ...
The standard can be compared visually to a suspension of bacteria in sterile saline or nutrient broth. If the bacterial suspension is too turbid, it can be diluted with more diluent. If the suspension is not turbid enough, more bacteria can be added. McFarland nephelometer standards:{2}
Methods for quantifying bacteria, changes in animal housing practices and sanitation, and many other factors may have changed the prevalence of Salmonella since that time. Also, such an approach often ignores the complicated fate and transport processes that determine bacteria concentrations from the source to the point of exposure.